This invention relates to a low density, large cross-section olefinic polymer foam structure blown with a blowing agent having a large proportion of 1,1-difluoroethane.
1,1-difluoroethane (HFC-152a) has become a preferred blowing agent for making olefin polymer foam structures because of its very low ozone depletion potential. HFC-152a has presented unique processing and extrusion problems because of its relatively low solubility in melts of olefin polymers.
Due to solubility problems, it has heretofore not been possible to make an olefin polymer foam structure in large cross-section and relatively low density with large proportions of HFC-152a. It would be desirable to have a process for making olefin polymer foam structures of large cross-section and low density using a large proportion of HFC-152a.